[dirtboy]

A popular predictor of future climate sensitivity is the change in global temperature produced by each doubling of CO2 in the atmosphere. This study confirms that in the Earth's past 420 million years, each doubling of atmospheric CO2 translates to an average global temperature increase of about 3 Celsius, or 5 Fahrenheit.

Unless, of course, the opposite is true - that an average global increase of 3 degress Celcius triggers a doubling of CO2 in the atmosphere.

[cogitator]

Unless, of course, the opposite is true - that an average global increase of 3 degrees Celcius triggers a doubling of CO2 in the atmosphere.

Still working on explaining this in my profile. You have to have a different radiative forcing factor capable of inducing that large a temperature change independent of atmospheric CO2 concentrations. The main secondary factor (speaking from the paleoclimate community perspective) in glacial-interglacial transitions was albedo. On Berner's timescales, erosion rates and plate tectonics are major players.